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Kmemleak patches 

Main features:
 - Handle percpu memory allocations (only scanning them, not actually
   reporting).
 - Memory hotplug support.
 
 Usability improvements:
 - Show the origin of early allocations.
 - Report previously found leaks even if kmemleak has been disabled by
   some error.
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Merge tag 'kmemleak' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux

Kmemleak patches

Main features:
- Handle percpu memory allocations (only scanning them, not actually
  reporting).
- Memory hotplug support.

Usability improvements:
- Show the origin of early allocations.
- Report previously found leaks even if kmemleak has been disabled by
  some error.

* tag 'kmemleak' of git://git.kernel.org/pub/scm/linux/kernel/git/cmarinas/linux:
  kmemleak: Add support for memory hotplug
  kmemleak: Handle percpu memory allocation
  kmemleak: Report previously found leaks even after an error
  kmemleak: When the early log buffer is exceeded, report the actual number
  kmemleak: Show where early_log issues come from
This commit is contained in:
Linus Torvalds 2012-01-14 18:11:11 -08:00
parent dca88ad691 029aeff5db
commit 892d208bcf
5 changed files with 155 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/kmemleak.txt
View File

@ -127,7 +127,10 @@ See the include/linux/kmemleak.h header for the functions prototype.
kmemleak_init - initialize kmemleak
kmemleak_alloc - notify of a memory block allocation
kmemleak_alloc_percpu - notify of a percpu memory block allocation
kmemleak_free - notify of a memory block freeing
kmemleak_free_part - notify of a partial memory block freeing
kmemleak_free_percpu - notify of a percpu memory block freeing
kmemleak_not_leak - mark an object as not a leak
kmemleak_ignore - do not scan or report an object as leak
kmemleak_scan_area - add scan areas inside a memory block

8
include/linux/kmemleak.h
View File

@ -26,8 +26,10 @@
extern void kmemleak_init(void) __ref;
extern void kmemleak_alloc(const void *ptr, size_t size, int min_count,
gfp_t gfp) __ref;
extern void kmemleak_alloc_percpu(const void __percpu *ptr, size_t size) __ref;
extern void kmemleak_free(const void *ptr) __ref;
extern void kmemleak_free_part(const void *ptr, size_t size) __ref;
extern void kmemleak_free_percpu(const void __percpu *ptr) __ref;
extern void kmemleak_padding(const void *ptr, unsigned long offset,
size_t size) __ref;
extern void kmemleak_not_leak(const void *ptr) __ref;
@ -68,6 +70,9 @@ static inline void kmemleak_alloc_recursive(const void *ptr, size_t size,
gfp_t gfp)
{
}
static inline void kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
{
}
static inline void kmemleak_free(const void *ptr)
{
}
@ -77,6 +82,9 @@ static inline void kmemleak_free_part(const void *ptr, size_t size)
static inline void kmemleak_free_recursive(const void *ptr, unsigned long flags)
{
}
static inline void kmemleak_free_percpu(const void __percpu *ptr)
{
}
static inline void kmemleak_not_leak(const void *ptr)
{
}

2
lib/Kconfig.debug
View File

@ -414,7 +414,7 @@ config SLUB_STATS
config DEBUG_KMEMLEAK
bool "Kernel memory leak detector"
depends on DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && \
depends on DEBUG_KERNEL && EXPERIMENTAL && \
(X86 || ARM || PPC || MIPS || S390 || SPARC64 || SUPERH || MICROBLAZE || TILE)
select DEBUG_FS

158
mm/kmemleak.c
View File

@ -100,6 +100,7 @@
#include <linux/kmemcheck.h>
#include <linux/kmemleak.h>
#include <linux/memory_hotplug.h>
/*
* Kmemleak configuration and common defines.
@ -196,7 +197,9 @@ static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
/* enables or disables early logging of the memory operations */
static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
/* set if a fata kmemleak error has occurred */
/* set if a kmemleak warning was issued */
static atomic_t kmemleak_warning = ATOMIC_INIT(0);
/* set if a fatal kmemleak error has occurred */
static atomic_t kmemleak_error = ATOMIC_INIT(0);
/* minimum and maximum address that may be valid pointers */
@ -228,8 +231,10 @@ static int kmemleak_skip_disable;
/* kmemleak operation type for early logging */
enum {
KMEMLEAK_ALLOC,
KMEMLEAK_ALLOC_PERCPU,
KMEMLEAK_FREE,
KMEMLEAK_FREE_PART,
KMEMLEAK_FREE_PERCPU,
KMEMLEAK_NOT_LEAK,
KMEMLEAK_IGNORE,
KMEMLEAK_SCAN_AREA,
@ -259,9 +264,10 @@ static void kmemleak_disable(void);
/*
* Print a warning and dump the stack trace.
*/
#define kmemleak_warn(x...) do { \
pr_warning(x); \
dump_stack(); \
#define kmemleak_warn(x...) do { \
pr_warning(x); \
dump_stack(); \
atomic_set(&kmemleak_warning, 1); \
} while (0)
/*
@ -403,8 +409,8 @@ static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
object = prio_tree_entry(node, struct kmemleak_object,
tree_node);
if (!alias && object->pointer != ptr) {
pr_warning("Found object by alias at 0x%08lx\n", ptr);
dump_stack();
kmemleak_warn("Found object by alias at 0x%08lx\n",
ptr);
dump_object_info(object);
object = NULL;
}
@ -794,9 +800,13 @@ static void __init log_early(int op_type, const void *ptr, size_t size,
unsigned long flags;
struct early_log *log;
if (atomic_read(&kmemleak_error)) {
/* kmemleak stopped recording, just count the requests */
crt_early_log++;
return;
}
if (crt_early_log >= ARRAY_SIZE(early_log)) {
pr_warning("Early log buffer exceeded, "
"please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
kmemleak_disable();
return;
}
@ -811,8 +821,7 @@ static void __init log_early(int op_type, const void *ptr, size_t size,
log->ptr = ptr;
log->size = size;
log->min_count = min_count;
if (op_type == KMEMLEAK_ALLOC)
log->trace_len = __save_stack_trace(log->trace);
log->trace_len = __save_stack_trace(log->trace);
crt_early_log++;
local_irq_restore(flags);
}
@ -846,6 +855,20 @@ static void early_alloc(struct early_log *log)
rcu_read_unlock();
}
/*
* Log an early allocated block and populate the stack trace.
*/
static void early_alloc_percpu(struct early_log *log)
{
unsigned int cpu;
const void __percpu *ptr = log->ptr;
for_each_possible_cpu(cpu) {
log->ptr = per_cpu_ptr(ptr, cpu);
early_alloc(log);
}
}
/**
* kmemleak_alloc - register a newly allocated object
* @ptr: pointer to beginning of the object
@ -872,6 +895,34 @@ void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
}
EXPORT_SYMBOL_GPL(kmemleak_alloc);
/**
* kmemleak_alloc_percpu - register a newly allocated __percpu object
* @ptr: __percpu pointer to beginning of the object
* @size: size of the object
*
* This function is called from the kernel percpu allocator when a new object
* (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
* allocation.
*/
void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
{
unsigned int cpu;
pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
/*
* Percpu allocations are only scanned and not reported as leaks
* (min_count is set to 0).
*/
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
for_each_possible_cpu(cpu)
create_object((unsigned long)per_cpu_ptr(ptr, cpu),
size, 0, GFP_KERNEL);
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
/**
* kmemleak_free - unregister a previously registered object
* @ptr: pointer to beginning of the object
@ -910,6 +961,28 @@ void __ref kmemleak_free_part(const void *ptr, size_t size)
}
EXPORT_SYMBOL_GPL(kmemleak_free_part);
/**
* kmemleak_free_percpu - unregister a previously registered __percpu object
* @ptr: __percpu pointer to beginning of the object
*
* This function is called from the kernel percpu allocator when an object
* (memory block) is freed (free_percpu).
*/
void __ref kmemleak_free_percpu(const void __percpu *ptr)
{
unsigned int cpu;
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
for_each_possible_cpu(cpu)
delete_object_full((unsigned long)per_cpu_ptr(ptr,
cpu));
else if (atomic_read(&kmemleak_early_log))
log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
/**
* kmemleak_not_leak - mark an allocated object as false positive
* @ptr: pointer to beginning of the object
@ -1220,9 +1293,9 @@ static void kmemleak_scan(void)
#endif
/*
* Struct page scanning for each node. The code below is not yet safe
* with MEMORY_HOTPLUG.
* Struct page scanning for each node.
*/
lock_memory_hotplug();
for_each_online_node(i) {
pg_data_t *pgdat = NODE_DATA(i);
unsigned long start_pfn = pgdat->node_start_pfn;
@ -1241,6 +1314,7 @@ static void kmemleak_scan(void)
scan_block(page, page + 1, NULL, 1);
}
}
unlock_memory_hotplug();
/*
* Scanning the task stacks (may introduce false negatives).
@ -1467,9 +1541,6 @@ static const struct seq_operations kmemleak_seq_ops = {
static int kmemleak_open(struct inode *inode, struct file *file)
{
if (!atomic_read(&kmemleak_enabled))
return -EBUSY;
return seq_open(file, &kmemleak_seq_ops);
}
@ -1543,6 +1614,9 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
int buf_size;
int ret;
if (!atomic_read(&kmemleak_enabled))
return -EBUSY;
buf_size = min(size, (sizeof(buf) - 1));
if (strncpy_from_user(buf, user_buf, buf_size) < 0)
return -EFAULT;
@ -1602,20 +1676,24 @@ static const struct file_operations kmemleak_fops = {
};
/*
* Perform the freeing of the kmemleak internal objects after waiting for any
* current memory scan to complete.
* Stop the memory scanning thread and free the kmemleak internal objects if
* no previous scan thread (otherwise, kmemleak may still have some useful
* information on memory leaks).
*/
static void kmemleak_do_cleanup(struct work_struct *work)
{
struct kmemleak_object *object;
bool cleanup = scan_thread == NULL;
mutex_lock(&scan_mutex);
stop_scan_thread();
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object_full(object->pointer);
rcu_read_unlock();
if (cleanup) {
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object_full(object->pointer);
rcu_read_unlock();
}
mutex_unlock(&scan_mutex);
}
@ -1632,7 +1710,6 @@ static void kmemleak_disable(void)
return;
/* stop any memory operation tracing */
atomic_set(&kmemleak_early_log, 0);
atomic_set(&kmemleak_enabled, 0);
/* check whether it is too early for a kernel thread */
@ -1659,6 +1736,17 @@ static int kmemleak_boot_config(char *str)
}
early_param("kmemleak", kmemleak_boot_config);
static void __init print_log_trace(struct early_log *log)
{
struct stack_trace trace;
trace.nr_entries = log->trace_len;
trace.entries = log->trace;
pr_notice("Early log backtrace:\n");
print_stack_trace(&trace, 2);
}
/*
* Kmemleak initialization.
*/
@ -1681,12 +1769,18 @@ void __init kmemleak_init(void)
scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
INIT_PRIO_TREE_ROOT(&object_tree_root);
if (crt_early_log >= ARRAY_SIZE(early_log))
pr_warning("Early log buffer exceeded (%d), please increase "
"DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
/* the kernel is still in UP mode, so disabling the IRQs is enough */
local_irq_save(flags);
if (!atomic_read(&kmemleak_error)) {
atomic_set(&kmemleak_early_log, 0);
if (atomic_read(&kmemleak_error)) {
local_irq_restore(flags);
return;
} else
atomic_set(&kmemleak_enabled, 1);
atomic_set(&kmemleak_early_log, 0);
}
local_irq_restore(flags);
/*
@ -1701,12 +1795,18 @@ void __init kmemleak_init(void)
case KMEMLEAK_ALLOC:
early_alloc(log);
break;
case KMEMLEAK_ALLOC_PERCPU:
early_alloc_percpu(log);
break;
case KMEMLEAK_FREE:
kmemleak_free(log->ptr);
break;
case KMEMLEAK_FREE_PART:
kmemleak_free_part(log->ptr, log->size);
break;
case KMEMLEAK_FREE_PERCPU:
kmemleak_free_percpu(log->ptr);
break;
case KMEMLEAK_NOT_LEAK:
kmemleak_not_leak(log->ptr);
break;
@ -1720,7 +1820,13 @@ void __init kmemleak_init(void)
kmemleak_no_scan(log->ptr);
break;
default:
WARN_ON(1);
kmemleak_warn("Unknown early log operation: %d\n",
log->op_type);
}
if (atomic_read(&kmemleak_warning)) {
print_log_trace(log);
atomic_set(&kmemleak_warning, 0);
}
}
}

12
mm/percpu.c
View File

@ -67,6 +67,7 @@
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <linux/workqueue.h>
#include <linux/kmemleak.h>
#include <asm/cacheflush.h>
#include <asm/sections.h>
@ -710,6 +711,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
const char *err;
int slot, off, new_alloc;
unsigned long flags;
void __percpu *ptr;
if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE)) {
WARN(true, "illegal size (%zu) or align (%zu) for "
@ -802,7 +804,9 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved)
mutex_unlock(&pcpu_alloc_mutex);
/* return address relative to base address */
return __addr_to_pcpu_ptr(chunk->base_addr + off);
ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
kmemleak_alloc_percpu(ptr, size);
return ptr;
fail_unlock:
spin_unlock_irqrestore(&pcpu_lock, flags);
@ -916,6 +920,8 @@ void free_percpu(void __percpu *ptr)
if (!ptr)
return;
kmemleak_free_percpu(ptr);
addr = __pcpu_ptr_to_addr(ptr);
spin_lock_irqsave(&pcpu_lock, flags);
@ -1639,6 +1645,8 @@ int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
rc = -ENOMEM;
goto out_free_areas;
}
/* kmemleak tracks the percpu allocations separately */
kmemleak_free(ptr);
areas[group] = ptr;
base = min(ptr, base);
@ -1753,6 +1761,8 @@ int __init pcpu_page_first_chunk(size_t reserved_size,
"for cpu%u\n", psize_str, cpu);
goto enomem;
}
/* kmemleak tracks the percpu allocations separately */
kmemleak_free(ptr);
pages[j++] = virt_to_page(ptr);
}